A display device using a non-self-luminous display panel such as, for example, a liquid crystal display panel is used typically in combination with an illumination device that illuminates the display panel from behind. An illumination device of this type uses any of various types of light sources including a cold cathode tube, a light emitting element, and the like. Examples of a light emitting element include a light emitting diode (hereinafter, referred to as “LED”), an organic electroluminescent element, an inorganic electroluminescent element, and the like, among which the most commonly used today is an LED. An illumination device described in Patent Document 1 also uses an LED as a light source.
In the illumination device described in Patent Document 1, as shown in FIG. 6, an LED 122 is mounted on a mounting substrate 121, and a lens 124 that covers the LED 122 is mounted to the mounting substrate 121. The mounting substrate 121, the LED 122, and the lens 124 constitute a light emitting module mj. A multitude of light emitting modules mj are disposed in a matrix form to form a planar light source.
While in the illumination device described in Patent Document 1, a multitude of point light sources are arranged, in an illumination device described in Patent Document 2, a multitude of linear light sources such as cold cathode tubes are arranged. In a case where, as described above, a display device is used in combination with an illumination device in which a plurality of light sources are arranged, if light from the light sources directly enters the illumination device, there occurs unevenness in brightness on a screen, and hence in order to prevent this, a diffusion plate that diffuses light is disposed between the light sources and the display device. As is also the case with Patent Document 2, a diffusion plate is generally used as a constituent component of an illumination device.
In a case where a multitude of point light sources are arranged to form a planar light source, when an increased area needs to be illuminated, a configuration may be required in which a plurality of mounting substrates each supporting a plurality of point light sources are arranged. Patent Document 3 shows one example of such a configuration.